The photograph in figure 1 displays a water cooled round convergent-divergent supersonic nozzle operating slightly overexpanded near 2460 F. The nozzle is designed to produce shock free flow near this temperature at Mach 2. The exit diameter of this nozzle is 3.5 inches. This nozzle is used in the present study to establish properties of the sound field associated with high temperature supersonic jets operating fully pressure balanced (i.e. shock free) and to evaluate capability of the compressible Rayleigh model to account for principle physical features of the observed sound emission. The experiment is conducted statically (i.e. M(sub f) = 0.) in the NASA/LaRC Jet Noise Laboratory. Both aerodynamic and acoustic measurements are obtained in this study along with numerical plume simulation and theoretical prediction of jet noise. Detailed results from this study are reported previously by Seiner, Ponton, Jansen, and Lagen.